Translations: Run po4a/update-po and cleanup unused strings

Translations: Run po4a/update-po and cleanup unused strings

The v5.2 branch won't get any translation updates so the fuzzy
strings and obsolete strings are all useless. Cleaning them up
makes the files smaller and less messy to compare.

    ./update-po

    for I in *.po
    do
        msgattrib --clear-fuzzy --clear-previous --empty \
                  --no-obsolete --no-wrap "$I" > tmp
        mv tmp "$I"
    done

The po4a run gave "Parse error at" message from fr.po but
after the fr.po was rewritten the error is gone.